In architecture, high transparency may be considered a desirable aesthetic quality of particular buildings and structures. In providing a glass construction, e.g. a loadbearing glass construction of glass elements, it may be preferable to maintain the transparency of the construction over as much of the area covered by the construction as possible, e.g. for aesthetic reasons. For example, in contemporary architecture, it may be preferred to provide transparent buildings, floors and/or walls.
Such high transparency may for example be applied in glazed façades and structural members, such as beams, columns, floors and roofs, constructed out of glass. As a result, glass may not only have a passive function in architecture, but also have an active, load-carrying function.
Nonetheless, glass is a brittle material, which may lead to unsafe failure behaviour. Key members such as structural beams are required to be robust, which means they should exert a gradual failure behaviour accompanied with relatively large deformations. For the case of structural glass beams, this can be translated into post-breakage strength and ductility. Conventional glass beams, as known in the art, e.g. comprising laminated glass, may have a brittle failure behaviour. Therefore, in order to increase their structural safety, redundancy must equally be increased, thus leading to an excessive, and costly, glass usage.
However, currently, practical applications may be mostly limited to relatively small spans and statically determinate support conditions. Nevertheless, it may be an aim in the architectural arts to construct large parts of a structure out of glass to create ever more transparent buildings, e.g. glass façades, floor and roof systems, or large-scale greenhouses.
Hybrid glass beam concepts, such as composite glass beams and reinforced glass beams, are known in the art in which glass is combined with another material, e.g. to improve post-breakage strength and ductility. Such structural glass beams may thus achieve a safer failure behaviour. Among these hybrid concepts, the stainless steel-reinforced glass beam, bearing some similarity to reinforced concrete, has proven to be relatively easily implementable in practice.
Particularly the steel reinforced glass beam, which may have been developed similar to reinforced concrete, may have advantageous properties. In this type, a small metal section, such as for example a steel alloy section, is added at the tensile edge of the glass beam, such as to serve as a crack bridge in case of glass fracture, transferring the loads between two intact glass zones, giving the beam post-breakage load-carrying capacity. Furthermore, the reinforcement is able to yield which gives the beam a ductile ultimate failure behaviour. Therefore, this type of hybrid glass beam may be particularly suitable as a bearing structural member.
To achieve a particularly transparent structure, entire systems of structural members should be preferably made of glass. For glass beam constructions, this may also imply a need for safe butt connections. Such beam system may, for example, be used to carry an entire floor or roof, to form a top-down glazed façade laterally supported by glass fins or to form simply a large-span glass beam.
The production process, e.g. autoclave dimensions, and transport may impose limits on the length of the beams. Several methods are known in the art for connecting such glass beams. Since dimensional limits are imposed by production and transportation, as well as by efficiency of on-site handling, a glass beam system in which glass beams are butt connected by safe connections may be preferable to construct such large scale spans.
A first kind of known connection approach is characterized by a steel member to which both glass beams are connected through bolts. In some prior art approaches, the steel member may be embedded in the interlayer of the glass laminate. However, such approaches may disadvantageously affect the overall transparency of the resulting beam negatively. Furthermore, a bolted connection may impose stress concentrations in the glass, while an embedment into the laminate may require all stresses to be transferred through the weaker interlayer, which mechanical properties highly depend on environmental conditions such as temperature and load duration.
Another approach known in the art is to create segmented glass beams, e.g. splice connected glass beams or glass beams connected by splice connections, in which the glass web exists out of multiple glass plies in its thickness and length direction. The segmentation scheme is typically chosen so that every section has a predefined amount of continuous glass panes. However, for beams with large span, this solution will lead either to a disadvantageous on-site production process, or to a very expensive and inefficient transportation procedure.
For example, a combination of a connector for glass elements and such glass elements to provide a loadbearing glass construction is known from US2005/0055941, in which a connection method is disclosed that comprises fitting a first fitting to a first loadbearing glass component, a second fitting to a second loadbearing glass component, and providing a glass load transmitting element between the first fitting and the second fitting.
In another prior-art example, US 2015/121802 also discloses a glass construction that comprises at least one glass post and at least one glass beam that are arranged adjacent to each other. A connector provides a rotationally fixed connection between the post and the beam. Along at least a part of the edges of the glass elements, reinforcement elements are provided that are connected to the connector by cooperating protrusions and receptacles.